Autogenerators



April 18, 1967 M. BOUVIER ETAL 3,314,403

AUTOGENERATORS Filed Feb. 1, 1965 MW x ta E Tm. N m m Vma T N T B United States Patent O 3,314,403 AUTOGENERATORS Maurice Bouvier, Villeurbanne, and Auguste Morroux,

Lyon, France, assignors to Societe dEtudes et de Participations, Eau, Gaz, Electricite, Energie, S.A., Geneva, Switzerland, a society of Switzerland Filed Feb. 1, 1965, Ser. No. 429,298 Claims priority, application France, Feb. 7, 1964, 963,088 3 Claims. (Cl. 123-46) This invention relates to gas-autogenerators, i.e. to machines comprising a motor cylinder preferably working on a two-stroke diesel cycle and at least one compressor cylinder for compressing air, at least most of which is supplied to the motor cylinder as feeding and scavengingair, t-he incompletely expanded combustion gases and the scavenging air forming, at the outlet of the motor cylinder, a mixture of hot pressurized gases which is supplied to a prime mover, such as a turbine, to drive the same.

The invention relates more particularly to free-piston autogenerators of this kind and still more particularly to autogenerators in which the compression and delivery stroke in one or several compressor cylinders coincides with the compression stroke in the motor cylinder.

In autogenerators of the kind specified, the motor cylinder is, as a rule, disposed inside an enclosure or casing to which one or several compressor cylinders deliver their compressed air, said casing therefore serving as a reservoir of air for feeding and scavenging the motor cylinder. The wall of said motor cylinder is provided with inlet ports which are uncovered by a motor piston, as the same nears its outer dead centre position, to connect the casing interior to the motor cylinder interior so that the air in the casing can enter the motor cylinder.

It is often found in the known autogenerators that, when the inlet ports of the motor cylinder are uncovered, a small proportion of burnt gases leaves the motor cylinder through said inlet ports and re-enters the casing, these gases carrying with them some lubricating oil which is deposited on the casing wall and soils the same.

It is a main object of the invention to obviate this disadvantage. According to a main feature of the invention, a closure-bounding wall is provided around the inlet ports of said motor cylinder, most of said wall being established within said casing and radially spaced from said inlet ports to define a space, between said motor cylinder and said wall, communicating with the space interior to the casing through at least one aperture disposed laterally of the ports.

Preferred embodiments of the present invention will be hereinafter described with reference to the appended drawing, said embodiments being merely given by way of examples.

FIG. 1 is a diagrammatic view in axial section of a free-piston type autogenerator with opposed pistons according to a first embodiment of the invention;

FIG. 2 is a view in axial section of a free-piston type autogenerator with opposed pistons according to a second embodiment of the invention, and

FIG. 3 is a section taken along the line III-III of FIG. 2.

The autogenerator comprises in known manner a motor cylinder 1 having a wall provided with inlet ports 2 and exhaust ports 3. Two opposed pistons 4 operate in the motor cylinder 1, each piston forming part of a piston assembly comprising one of the motor pistons and a compressor piston 5 operating in a compressor cylinder 6. When in their outer dead centre position the motor pistons 4 uncover the ports 2, 3, as shown in the drawings. The two respective piston assemblies 4, 5 are interconnected in known manner by synchronising means which are not shown.

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Preferably, the driving part of the autogenerator formed by the cylinder 1 and the motor pistons 4 operate on a two-stroke diesel cycle, in which event fuel is injected in known manner by one or more injectors (not shown) when the pistons 4 are in or near their inner dead centre position.

Each compressor piston divides its cylinder 6 into two compartments 6a, 6b. The compartment 6a on the inward side of each piston 5 forms the actual compressor cylinder and accordingly is provided with inlet valves 7 and delivery valves 8; the compartment 6b on the outward side of each piston 5 forms a pneumatic accumulator which, during the outwards stroke of the piston assemblies, stores in its air cushion most of the energy developed in the motor cylinder 1 during the operative, i.e. outwards, stroke of the pistons 4 to subsequently restore this energy to the piston assemblies during the compression, i.e. inwards stroke. During their outwards stroke the compressor pistons 5 suck air into the compartments 6a through the inlet valves 7 and, during their inwards stroke, compress such air, to deliver it through the valves 8 to a casing 9 which extends around the motor cylinder 1 and which forms the reservoir of air for scavenging and feeding the cylinder 1. Such air can enter the cylinder 1 when the motor piston 4 associated with the inlet ports 2 starts to uncover the same.

According to the main feature of the invention, the inlet ports 2, instead of opening directly into the interior of the casing 9, are surrounded by a wall or an enclosure which forms in the casing 9 a collector separate therefrom but in constant communication therewith.

In the embodiment illustrated in FIG. 1, the enclosure is bounded by a cylindrical Wall 10 disposed entirely within the casing 9, facing the ports 2 concentric to and spaced apart from the cylinder 1. The annular gap thus left between the wall 10 and the wall of the cylinder 1 is closed at one end by an annular end member 11 and at its other end communicates with the inside of the easing 9. Consequently, the small amounts of oily gas which may escape from the motor cylinder through the inlet ports 2 when the cylinder 1 is scavenged, are collected in said enclosure 10 and thus cannot spread out inside the casing 9 and the oil contained in such gas cannot soil the casing 9.

The scavenging air from the casing 9 passes through said annular gap and through the ports 2 to be mixed with the combustion gases inside the cylinder 1, so that a mixture of combustion gases and scavenging air leaves the cylinder 1 through the exhaust ports 3 which are surrounded by an exhaust collector 12 connected to an exhaust duct 13 of the autogenerator, the duct 13 being connected to the inlet, for instance, of a turbine.

In another embodiment of the invention, the enclosure surrounding the inlet ports 2 is provided or is preceded by a cooler for cooling the supply and scavenging air before the same enters the cylinder 1. In the embodiment shown in FIG. 2, the enclosure around the inlet port 2 comprises a wall 16 surrounding said ports and radially spaced therefrom, part of said wall projecting outside from the walls of the casing 9, and two radial partitions 14, 15, longitudinally spaced from the ports 2 and on both sides thereof, connecting the sides of said wall 16 and the motor cylinder 1. The space interior to said wall 16 and partitions 14 and 15 communicates with the space within the casing 9 on bot-h the exterior sides of the partitions 14 and 15 through a duct 17, provided outside of said casing 9 and comprising a cooler 18 through which the said scavenging and feeding air is supplied from the air reservoir casing 9 to the inlet ports 2 when the latter are uncovered by the corresponding piston 4. The path followed by the air is indicated by arrows in FIG. 2. The cooler 18 can in turn be cooled by a water flow which may or may not form part of the autogenerator cooling system; alternatively, an air flow produced, for instance, by a fan can cool the cooler.

As the previous embodiment, this embodiment, too, prevents, soiling of the inside of the casing 9 by any oil vehicled along by the combustion gases from the cylinder 1 when the ports 2 are open.

While the invention has been described hereabove with particular preferred embodiments, it will be understood that the invention is not limited to those embodiments, but is intended to encompass all alternatives, modifications and equivalents as may be properly included within the spirit and scope of the invention as defined by the appended claims.

What is claimed is:

1. A free piston gas autogenerator comprising a motor cylinder and a motor piston reciprocating therein, an air reservoir casing surrounding said motor cylinder, the volume of the former being greater than the volume of the latter, compressor means comprising a compressor cylinder and a compressor piston reciprocating therein to feed compressed air into said casing, inlet ports positioned in said motor cylinder to be uncovered by said motor piston when the same approaches one of its dead end centres, an enclosure comprising a peripheral wall, at least the greatest portion of which is within said casing, radially spaced from said intake ports, said enclosure defining around the same a space separated from the internal space of the casing and comprising a free opening longitudinally offset with respect to said inlet ports permitting the communication with each other of said spaces.

2. A free piston gas autogenerator according to claim 1 wherein the said enclosure as completely inside of said casing, its peripheral wall being substantially concentric to said motor cylinder and extending on either side of said inlet ports, said enclosure further comprising a radial wall portion connecting, on one side of said inlet ports, said peripheral wall to said motor cylinder.

3. A free piston gas autogenerator according to claim 1 wherein said enclosure projects partially outside from said casing, the borders of the portion of said peripheral wall internal to said casing being connected by radial wall portions, on the one hand, to the motor cylinder on both sides of said inlet ports and, on the other hand, to the walls of said casing, said free piston gas autogenerator further comprising an opening in said casing, outside of said enclosure, and duct means connecting said opening to the outside projecting part of said enclosure.

References Cited by the Examiner UNITED STATES PATENTS 1,976,286 10/ 1934 Kreidler 12351 2,167,946 8/1939 Gray 12371 2,783,750 3/1957 Horgen 123-46 MARK NEWMAN, Primary Examiner.

WENDELL E. BURNS, Examiner. 

1. A FREE PISTON GAS AUTOGENERATOR COMPRISING A MOTOR CYLINDER AND A MOTOR PISTON RECIPROCATING THEREIN, AN AIR RESERVOIR CASING SURROUNDING SAID MOTOR CYLINDER, THE VOLUME OF THE FORMER BEING GREATER THAN THE VOLUME OF THE LATTER, COMPRESSOR MEANS COMPRISING A COMPRESSOR CYLINDER AND A COMPRESSOR PISTON RECIPROCATING THEREIN TO FEED COMPRESSED AIR INTO SAID CASING, INLET PORTS POSITIONED IN SAID MOTOR CYLINDER TO BE UNCOVERED BY SAID MOTOR PISTON WHEN THE SAME APPROACHES ONE OF ITS DEAD END CENTRES, AN ENCLOSURE COMPRISING A PERIPHERAL WALL, AT LEAST THE GREATEST PORTION OF WHICH IS WITHIN SAID CASING, RADIALLY SPACED FROM SAID INTAKE PORTS, SAID ENCLOSURE DEFINING AROUND THE SAME A SPACE SEPARATED FROM THE INTERNAL SPACE OF THE CASING AND COMPRISING A FREE OPENING LONGITUDINALLY OFFSET WITH RESPECT TO SAID INLET PORTS PERMITTING THE COMMUNITION WITH EACH OTHER OF SAID SPACES. 